JPS59103301A - Temperature sensitive resistance element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature-sensitive resistance element, and particularly to a temperature-sensitive resistance element for electric power.

A temperature-sensitive resistance element (positive temperature coefficient thermistor) is a ceramic semiconductor whose resistance increases rapidly when the temperature exceeds a certain temperature. ! Minutes of product! I! In r, it is used as a constant temperature photothermal body, a non-contact switch, a constant current device, or a current limiting element.

However, the above-mentioned temperature-sensitive resistance element is for power use (large current use)
When used as a current limiting element in There are problems such as a sudden decrease in temperature due to short circuit current and thermal breakdown.

The present invention was made in view of the above-mentioned problems, and its purpose is to reduce the specific resistance at room temperature and increase the mechanical resistance, so that it can be used as a current limiting element for P1 power. An object of the present invention is to provide a temperature-sensitive resistance element. Embodiments of the invention will now be described in detail with reference to the drawings.

The temperature-sensitive resistance element according to the present invention is used as a power current-limiting element connected to the power supply side of a circuit, for example, to reduce the load of a device. A molded body of a mixed powder in which 1 to 30% by weight of nickel powder is mixed with powder is sintered at a temperature of 1150 to 1500°C in a vacuum, reducing or inert atmosphere, and this sintered body is oxidized. 900-1450℃ in atmosphere
It is oxidized at a temperature of

Here, the ratio of nickel to barium titanate is 3
If the amount exceeds 0%, sintering becomes difficult, and by sintering at a temperature within the above range, the nickel powder interposed in the barium titanate powder becomes sintered. It not only promotes consolidation, but also functions as a binder, thereby increasing the mechanical strength of the element. moreover,
The reason why the sintered body is oxidized is to reduce the specific resistance R of the element at room temperature.

This is to reduce the ratio of resistivity Rt at high temperature to Rt/Ro2Q; however, if the temperature exceeds 1450°C, nickel will oxidize and the resistivity Ro at room temperature will become even lower, so it must be avoided.

The above-mentioned temperature-sensitive resistance element is manufactured by adding pure water to a titanium-free barium powder whose particle size is 50 to 100% less than 1 μm, and placing it in a ball mill with an all-plastic lining (Teflon coating). Ball mill 26-3 at 75-85 revolutions per minute using agate spherical boulders
The powder is pulverized by operating for 0 hours, and then dried in air at 120° C. for 2 hours or more and passed through a mesh sieve (9) to obtain a single-mesh barium titanate powder.

Also, pure 999.9 chinitsukel powder? ] Pass through a 250 mesh sieve to obtain 1250 mesh nickel powder.

Then, in a V-shaped rotary mixer made entirely of glass, alcohol (reagent special grade ethanol) was mixed with powder of titanate of 1 to 301 [mets] and 2' titanate powder of 1 to 250 mesh. 3 to ensure even mixing.
The mixture is mixed for 0 to 60 minutes, and then the alcohol is removed by scattering and evaporation to form a dry mixed powder.

The above-mentioned mixed powder was put into a mold and 250Kr/
A disk-shaped molded body having a predetermined diameter and thickness considering the yield Rdk due to sintering is made by pressurizing at a pressure of (
0.5 to 10 at a temperature of 1150 to 1500°C (preferably 1.250 to 1350°C) in argon gas)
It takes time to sinter.

The rate of temperature rise and fall during heating and cooling is 300° C.h or less, and 200° C./h is appropriate from the viewpoint of stabilizing properties and productivity. The primary sintering atmosphere is not limited to an inert atmosphere, but may be a vacuum or a reducing atmosphere (hydrogen gas).

Finally, the above-mentioned sintered body was placed in air at a temperature of 900 to 14
Oxidation treatment is performed at a temperature of 50°C for 0.5 to 10 hours to complete the desired temperature-sensitive resistance element.

Note that the rate of temperature rise and fall during the oxidation treatment is 300° C./h or less, as in the case of sintering. Further, the atmosphere for the oxidation treatment is not limited to air, but may be any oxidizing atmosphere such as oxygen-rich air or fc oxygen.

The temperature-sensitive resistance element (diameter 3
In order to avoid affecting the properties of the floor body, the R-T was measured by brush-coating In-Ga alloy powder paste to form electrodes.
A comparison of the percentage properties with the conventional one is shown in Figure 1. In other words, in Figure 1, the horizontal axis is the temperature T (°C), and the vertical axis is the specific resistance R (Ω・cIn)' on a logarithmic scale.
Curve A shows a barium titanate powder compact sintered in air at a temperature of 1250°C for 1 hour, and curve hB shows a barium titanate powder compact sintered in argon. 1 at a temperature of 1250°C in gas
The one sintered over time, and shown by curve B', is
A molded body of titanium-imitating barium powder was placed in argon gas at a temperature of 1250°C for 1 hour! ! Curve 0 shows the molded body of a mixed powder of barium titanate and nickel, which was sintered in air at a temperature of 1250°C for 1 hour. R- of the product according to the present invention, which was sintered at a temperature of 1250°C for 1 hour in the air, and the sintered body was oxidized in the air at a temperature of 1250°C for 1 hour.
It is a T characteristic.

Therefore, it can be seen that the specific resistance of the temperature-sensitive resistance element according to the present invention at room temperature is about 40°, which is about δ smaller than that of the conventional one.

In addition, the temperature-sensitive resistance element according to the present invention has a specific resistance Ro (Ω, ) and the specific resistance Rt (Ω-crn) at a certain temperature 1 (240°C) relative to the specific resistance Ro at room temperature
The ratio Rt/Ro was as shown in FIG. 2(a) and FIG. 2(bl), respectively.

Therefore, it can be seen that good results are obtained when the content of nickel relative to barium titanate is 1 to 30% by weight.

Furthermore, in the temperature-sensitive resistance element according to the present invention, the amount of nickel added to barium titanate is '! 1 = 10ffii%, and when the temperature T (℃) of oxidation treatment is changed, the specific resistance Ro (Ω・σ) at room temperature and the specific resistance Rt (Ω) at a certain temperature (240℃) with respect to the specific resistance Ro at room temperature
-cnI) ratio Rt/Ro is shown in Figure 3 (a
) and as shown in Figure 3(1)l.

Therefore, it can be seen that the oxidation treatment temperature is preferably in the range of 900 to 1450°C. It should be noted that if the temperature exceeds 1450°C, the specific resistance Ro at room temperature will suddenly increase, so it must be avoided.

In addition, the sintering temperature T (℃) of the compact and the density ρ of the element
The relationship with (g/cr/l) is as shown in Figure 4.

Therefore, it can be seen that the sintering temperature is preferably in the range of 1250 to 1350°C, and the product can be made more compact as shown in FIG.

The improvement in the mechanical strength of the temperature-sensitive resistance element is due to the fact that, as mentioned above, nickel acts as a binder that binds barium titanate particles, and also contributes to improving the thermal conductivity of the element itself, improving heat dissipation efficiency. This seems to be due to being praised.

As described above, the present invention is a temperature-sensitive resistance element made by completely destroying a barium sintered body of titanium containing 1 to 30% nickel by weight. It is possible to reduce the width to a large extent, improve the mechanical strength, and furthermore, it can be used as a current limiting element for electric power.

[Brief explanation of the drawing]

Fig. 1 is an RT% relationship diagram comparing the temperature-sensitive resistance confectionery of the present invention with conventional confectionery, Fig. 2 (al and Fig. 2 ft)
Figure 3(a) and Figure 3( 1))) are the specific resistance at room temperature when the oxidation treatment temperature is changed, and H to the specific resistance at room temperature. FIG. Figure 1 T('C)

Claims (1)

[Claims] A temperature-sensitive resistance element obtained by oxidizing a sintered body of barium titanium alloy containing 1 to 30% by weight of nickel.